php, fun!

Hello there. I'm using popen to run some programs that output a text blob after several seconds. I'm using fgets to read from the processes stdout, but when I do that fgets just hangs until the process finally does output the text. What I want is to check to the stdout, and if nothing was output then to move on.

tl;dr I want to check if the process is done, if it isn't then I want to have the program do something else and come back to it later. Help.

http://php.net/manual/en/function.stream-set-blocking.php

_{^{I've helped him!}}